Attaching means and assembly method for slotted tube and tip member of a mechanical pencil



March l3, 1951 c. N. JOHNSON 2,544,759

ATTACHING MEANS AND ASSEMBLY METHOD FOR SLOTTED TUBE AND TIP MEMBER OF A MECHANICAL PENCIL Filed Aug. v, 1948 FIG. 2

INVENTOR CLIFFORD N. JOHNSON 3 ATTORNEY Patented Mar. 13, 1951 ATTACHING MEANS. .AND ASSEMBLY METHOD FOR SLOTTED TUBE AND TIP MEMBER OF A MECHANICAL PENCIL Clifiord N. Johnson, St. Louis, Mo., assignor to Ritepoint Co. St. Louis, Mo., a corporation of Missouri Application August 7, 1948, Serial No. 43,147

This invention relates to mechanical pencils, generally, and concerns itself more particularly with an improved means and method for securing the lead guide tubes thereof to their tip members.

Itis an object of the invention to provide a simplified device and method for securing the lead guide tube of a mechanical pencil to its tip member which will prevent a separation of the parts, a turning of the tube in the tip member, and a loosening of the pencils spiral feed.

Itjsalso an object, of the invention to provide a means and method for securing the lead guide tube of a mechanical pencil to .its tip member, which will carry out the foregoing object, yet is simnle 'and economical to make and practice.

Other objects and advantages will become apparent as the specification proceeds and a more comprehensive understanding of the invention will be afforded from the following detailed re-' scription when considered in coniunction with the (accompanying drawing, in which g Fig. l is an exploded elevational view of a mechanical pencil unit embodying the instant invention;

Fig. 2 is a vertical sectional view of a tip member and lead guide tube employed in the unit illustrated in Fig. 1, taken along a line 2-2 indicated on Fig. 3 and showing a means for securing these parts together; and

Fig. 3 is a top view of the tin member and lead 5 Claims. (01- 120-18) guide tube, only, of the unit illustrated in Fig. 1,

showing these parts assembled.

Briefly stated, the invention contemplates a lead guide tube in which two transverse grooves are channeled on opposite sides of the tube near one of its ends. This particular end of the tube is inserted in a tube receiving bore of the tip member, to which it is to be attached, so that the top walls of the aforementioned grooves lie slightly above the mouth of the tube receiving bore. Within the tip member a larger bore, lying directly above the tube bore, is made which is adapted to receive a special swaging tool. This tool is hollow so as to slide over the lead guide tube and carries on its tool end a swaging die mounting three swaging elements. Two of the latter elements are arranged to upset material from the body of the tip member to form two small lugs, which, in the same swaging operation, are driven respectively into the grooves formed on the lead guide tube. These lugs engage the tube to hold it fast in the top member. The third swaging element forms a third lug anddrives it into the slot of the lead guide tube,

as a swaging toolreceiving bore. 11in turn, connects with a lead guide tube bore I3,

ibore' I4. connects with the bore I4.

.and bearing washer 22.

2 which prevents the same from turning in the tip member. With this method, the tube is secured to its tip member with a single swaging operation.

The above described means and method for securing a lead guide tube of a mechanical pencil to a tip member thereof finds its use and applica- 'tion in the device illustrated in Fig. 1. Here, a tip member I I is provided in which there is drilled a plurality of connecting bores.

As shown in Fig. 2, a bore I2 is made at the top of the tip member II, which may be termed The bore I2,

and the latter communicates with a lead carrier Finally, a'lead bore I5 is made which The other elements of the mechanical pencil device, shown,.ar'e a bearing washer I6, a ferrule II, spiral I8, lead carrier I9, lead guide tube 2I, As assembled, these parts are arranged as follows.

The lead guide tube 2| is attached to the tip member II in a manner later .to be described, and the spiral I8 is staked into the ferrule I! by means of a pin 23,'carried on the former, engaging a groove 24 on the latter. The lead carrier I9 is passed into the lead guide tube 2I so that a lug 25 on the former rides in a longitudinally extending slot 26 in the latter. Next, the bearing washer IS, the spiral I8 and its attached ferrule I! is passed over the lead guide tube 2I so that the former rests in the bottom of the bore I2 in the tip member II with the ferrule I1 bearing on the washer IS. The spiral [8 receives the lug 25 in a spiral slot 21 formed therein and is held in compression by the bearing washer 22, all in a manner well known to the art, a pin 28 holding the washer 22 on the tube 2!.

The fact that the spiral I8 is held in compression between the bottom of the bore I 2 and the bearing washer 22 attached to the tube 2 I, makes it necessary that the tube and tip member be securely attached to each other. Moreover, since it is a function of the lead guide tube 2| to guide the lead carrier I9 in a straight path, this tube must not turn in its bore I 3.

Accordingly, thetube 2| is secured to the tip member I I in the following manner. Two transverse grooves 29 and 3| (Fig. 2) are channeled in the lead guide tube 2I near the end thereof so their top walls lie slightly above the bottom of the bore l2 whenthe tube is in place in its bore I3. Next, by means of a special tool, two lugs,

or ears, 32 and 33 are swaged from the metal of the tip member I I and driven, respectively, into the grooves 29 and 3|. By means of the same special tool, and at the same time the lugs 32 and 33 are formed, a third lug 34 (Fig. 3) is struck from the metal of the tip member II and driven into the slot 26 of the tube 2 I, to prevent the turning of the tube in the tip member.

With regard to the economies of the means and 4 method taught, it is to be pointed out that the without the whole and improvements may be added while retaining some or all of the advantages of the invention.

What is claimed is:

1. A method for attaching a slotted lead. guide tube to a tip member of a mechanical pencil, comprising the steps of boring said tip member to receive said tube, forming a transverse recess -in the tube, inserting said tube within the bore, and swaging metal from the edge of said bore into said recess and the slot and in holding engagement with said tube at the point where said tube emerges from-said bore.

- 2. A- method of attaching a slotted lead guide .tube to atip member oi a mechanical pencil comprising the steps of boring said tip member to receive said tube, counterboring said tip to form a swaging tube bore above and concentric with said tube bore, forming a transverse recess in said tube, and swaging lugs from the metal at the edge ofsaid tube bore into recess and the slot and in holding engagement with said tube at .the point where said tube emerges from said bore.

3. In a mechanical pencil having a lead guide tube with a longitudinal slot and having its end inserted in a bore in a tip member, improved means for securing said tube in said tip member, comprising a lug formed from the body of said tip member at the edge of the bore turned into said longitudinal slot in said lead tube, a transverse channel in the tube, and a second lug similarly formed from the edge of said bore turned into said transverse channel in said tube.

4. In a mechanical pencil having a lead guide tube with a longitudinal slot and a tip member, improved meansv for securing said tube in a tube bore in said tip member, comprising a shoulder formed by a counterbore above and concentric with the tube bore in the tip member, a transverse channel in the tube, and at least two lugs struck from the edge of said shoulder and engaging respectively in said longitudinal slot and said channel in said guide tube.

5. In a mechanical pencil having a slotted lead guide tube and a tip member, means for securing said tube in a bore in said tip comprising a transverse channel in a wall of the tube at a point where the tube emerges from the tip in assembled relation, a first lug struck from the tip member at the mouth of the bore and turned into the groove, and a second lug similarly struck from the mouth of the bore and turned into a slot, in said. tube.

CLIFFORD N. JOHNSON.

REFERENCES orrnn lfhe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,172,349 Hauton Sept. 12, 1939 2,268,787 Wales Jan. 6, 1942 

